No Stern Ramp for Boats on the OPC–Mistake?

The National Security Cutter (NSC) incorporates a stern launch for two of it’s boats. It is one of its most celebrated features. But the Offshore Patrol Cutter (OPC) specifications, surprisingly, explicitly excluded any consideration of this feature. Is this a mistake?

I’ve had reservations about using stern launch on large ships, because I could imagine that as the ship pitches, the boat and the stern of the ship could move up or down at very different rates, even in different directions, perhaps dangerously so. Still training and good technique can mitigate dangers, so I hope to hear form someone with first hand experience with the system, particularly coxswains who have done both stern ramp and conventional recoveries.

Are there circumstances that preclude using the stern ramp recovery? What is the best heading relative to the sea? Comments, please.

31 thoughts on “No Stern Ramp for Boats on the OPC–Mistake?

  1. I think the biggest reason USCG wants to stay away from stern ramps is cost due to size increase.

    For a ship the size of the OPC, the length is largely driven by the flight deck and hangar space. By adding a stern ramp for larger boats like the 26 ft OTH IV, they are committing to at least another 30 additional feet of ship aft of the flight deck that occupies a lot of volume, which is at least a 10% increase from the projected lengths. Bigger ship means more HP, more fuel, more initial cost.

    Structurally, there is a lot of buoyancy and strength lost with a stern ramp. Additional structure (weight and volume) is required in the vicinity of the stern ramp. It also prevents the use of a stern flap, which has proven to give a good efficiency boost to transom-sterned ships in the pre-planing speed range.

    Good article on stern ramp viability here: http://www.columbiagroup.com/newsletters/TCG%20Pulse%20Winter%202011.pdf

    • Thanks, Graham, still you would have thought they would have left it as an option to be mixed with other design considerations rather than specifically excluding if that were the only consideration. (Appreciate the reference.)

  2. I agree with Graham completely! A stern ramp cannot be retrofitted easily, if at all. It is a design decision to me made upfront. What is wrong with using modern davits to L&R boats? They are much more capable than almost any seen on USN & USCG ships. And one can probably mount two on OPC giving a distinct operational improvment.

    • It will take longer to launch the small boats on invading a go fast on a drug bust. And it will allow more lives to be saved. I am a Coast Guard Veteran.

  3. I spent many an hour repairing both the stern launch mechanisms as well as the small boats due to the complexities a stern launch introduces. While onboard BERTHOLF, only jet-drive Small Boats were able to utilize the stern ramp; however non-NSC vessels have Launched/Recovered outboard-driven SBs. To (sort of) answer your question: yes, there are favorable headings the ship should maintain for stern launch/recover operations (but I believe going into more detail than that would be an OPSEC hazard, and although Nobody Important is NOT holding a gun to my head as I type this, I don’t think it’s a good idea to elaborate on those sort of operational hinderances). Obviously, the more extreme the sea state and/or ship’s speed, the more difficult (and therefore dangerous when you have a 5-ton small boat in close proximity to a 4450-ton cutter) the operation is. The article Graham points out is descriptive and accurate. I also have first-hand experience of being the coxswain while recovering a small boat in the stern launch. It is an extremely demanding process and, because it was the first time I had ever attempted was unable to do it. However, even the Boatswains Mates onboard had trouble completing the task–even the best coxswains onboard had difficulty recovering when weather got rough (and consequently I got to spend those hours conducting repairs as mentioned earlier).

    Basically what it comes down to is how well does the design to protect the stern launch and small boats and how well trained are the people. Operationally, it is an amazing feature to have and makes Launch/Recover of small boats easy and quick when seconds matter in SAR or LE ops. The stern launch, when used to the maximum capability, requires much less attention than a davit; however if improperly maintained or trained, a lot could go wrong. Another down-side to the launch is the single point of failure of the stern door: if you can’t open it, you cannot launch any more small boats. There really is a lot to consider with this decision, but I am inclined to base it on this:

    The first NSC had a cornucopia of complications with its stern launch system, and the Coast Guard, like the government, has a tendency of overcorrecting its problems i.e. removing the stern launch system from future Deepwater assets rather than listening to the BMs and MKs that actually operate and maintain the system in order to improve upon the overall design.

    I am curious what Stern Bays have to offer. I have never seen one in action but understand they are reliable and versatile, and think that USN and USCG should look more into those as viable options. What kind of pros and cons are associated with them and what are their requirements (I’m assuming they would only be feasible for longer and/or wider vessels)?

      • Sorry, I used the wrong term. I’m not too privy to it (hence why I’m curious about them), but I believe the naval term is “well deck.” The Navy uses them on most amphibious ships and is a similar concept, except the entire ship moves in order to operate it. I’m assuming that it makes the vessel slow, structurally susceptible, and especially takes up a lot of valuable room. I’m not saying put a well deck on the OPC or NSC, since I’ve never seen one in action nor have I talked to someone who has.

        The Coast Guard is more about its detachments than it is the large units, which is why the NSC is being praised: it can carry multiple helicopters and multiple small boats, launching and recovering them non-stop (at great strain to the crew, however). For LE and SAR it’s the same concept: get as close to the scene as possible, deploy a helicopter to find/track the target, then deploy a small boat to intercept. The cutter that can carry the most assets while still getting on-scene quickly will be the most successful (assuming the assets deployed onboard are ALSO appropriately designed).

      • Matt, Thanks for the reply. No, I don’t think we want to try a well deck. It is a much slower process. The ship stops and ballast down to flood the well deck that is normally dry. It does take up a lot of room. The ships are not necessarily slow, they do 20-24 knots, but they are all very large.

    • In other words, when everything works the way it is designed, a stern launched boat gives a cutter a significant operational advantage. When everything doesn’t work the way it is designed, you have less capability – or even no capability.

      I think that it is no surprise why the OPC specs specifically eliminated it.

    • Matt while you provide good operational insights into a stern ramp L&R, I was addressing the issue from the ship design and naval architecture viewpoint. One cannot simply add on such a system, it has to be built INTO the original ship design to be done right. I believe the USCG has had some recent negative experience with “tacking on” stern ramps?

      But equally as important, you did not even address davits. Which are cheaper, can be added to a degree and can be sized to fit newer/different boats however engined.

      • Leesea,
        Correct, I was not replying to your previous post, but if you request comments, then I’ll be happy to oblige. Being a Naval Engineer with the CG that now works with WPBs (which I found out the hard way that the failed 123′ stern ramp project is still a sore subject around here), I fully understand the complications involved with simply “adding” structure changes without fully analyzing material fatigue.

        I didn’t address davits because I didn’t feel they need addressing: they are tried and true. All the pros you mentioned are correct. I would add also that they are also easier to maintain and the CG has a history with them, so most people know how to fix them IF they do malfunction. However, some of the cons associated with davits:
        –It is much more weather dependent and even the best coxswain in the world cannot alleviate some of the dangerous conditions
        –It takes two to three times more people to L/R than witha stern ramp system. THIS IS HUGE.

        The Coast Guard is trying to do more with less, and reducing the required crew size or enabling multiple missions to be performed simultaneously is advantageous for the small, yet strong service.

        I prefer neither stern ramp nor davits, but I do believe that we (Coast Guard, Military, Government, etc) should always work on improving. The CG has a habit of scrapping things rather than improving them (although, sometimes scrapping IS an improvement), and “It’s always been that way” is often a cop-out for putting in an extra effort to develop a better method. Unfortunately it usually has to do with the miniscule budget the CG is appropriated.

      • Matt, I agree personnel costs have to be factored in. What is the weather envelop for stern ramps?

        I have noted that davits and cranes have “gone away” from amphib warships as well which I think is a serious omission.

      • Agreed, ships should always have a tried-and-true fall-back plan for these matters.

        Regarding the envelope, I believe the small boats needed special authorization to be deployed if the seas were greater than 4ft swells; however that authorization is often necessary. Having said that, safety with the stern ramp didn’t become a big concern until 8ft. Don’t bring that to the bank, I spent more time supervising fire drills than small boat ops.

  4. There are two potentially catastrophic ways a recovery can fail using this system aside from simply coming in off center.

    1. The boat might power forward off the top of a swell just as the stern of the ship is falling away and essentially fall several feet into the well.
    2. The boat might power forward as the ship pitches forward raising the stern and the boat goes below the lip of the well. The stern then comes down on the boat’s bow.

    Both of these are closely related to the ship’s pitch, its frequency and amplitude, which you would presumably want to minimize. That suggest a quartering sea might be safest if the weather is dicey.

    Training and technique can minimize danger, but if you do thousands of recoveries sooner or later the odds will catch up with you. It is probably a good idea to consider worse case scenarios.

  5. Interesting insights on the downsides of stern ramps. They’re obviously still in their infancy, but is seems like there are a number of avenues for improvement.

    One of the most interesting designs I’ve heard involves slow recovery via a towing cable, inspired from fishing boats. This is being trialed on the new 290ft French OPV and appears to eliminate most of the risks/damage from gunning a RHIB at high speed into a tight space. It also eliminates the submerged part of the ramp, alleviating some of the buoyancy issues. It does require a few more motors & moving parts though.

    Diagrams of how this works are in the patent application: http://worldwide.espacenet.com/publicationDetails/originalDocument?FT=D&date=20110325&DB=EPODOC&locale=en_EP&CC=FR&NR=2950317A1&KC=A1

    • Very interesting, perhaps with some innovations like these, the process can be simplified and training and good judgment may become less critical–a sign of the best inventions.

      Do you know if this system is the one on the new French Offshore Patrol Vessel L’Adroit?

      • I believe so. I can only go by public sources, but that patent fits exactly the stern launch system described (in much less detail) for Adroit, down to the schematics which have a remarkable likeness to the real ship. And the patent holders are definitely right (DCNS & Bopp).

      • At less than 1500 tons full load and 85 m (285′) in length, the L’Adroit (http://en.wikipedia.org/wiki/L%27Adroit) seems to prove that stern launch does not necessarily have to add much if anything to the size of the ship, but the stern and fantail is still a unique space that might be better used for other things.

        The Navy has also made a substantial commitment to the stern launch system. They have built, contracted, or optioned 24 ships, and plan to build to a total of 55 with these systems.

        As we gain experience, if we find that the NSC’s stern launch/recovery system is problematic, a look at the French system might be worthwhile.

      • Any idea how the French attach the line to the bow of the rigid hull to pull it in? Seems as if a messenger or some other system would have to be permanently rigged. Then, of course, that would establish a weak point in the recovery line.

        I’d have to see it in action.

    • In the 19th Century, the 75-foot or smaller revenue cutters regularly towed the 24-16-foot barge behind to make working room on deck. However, they could slow retrieve (hand over hand) the boat and hoist it on deck if necessary.

      If folks think taking a small boat into a stern retrieving system is tight, try riding on an LCAC and going into the well deck of a LHA. I know there is enough room but it is pretty scary in the squeeze.

    • DCNS built that in only 18 months plus one month off for vacation. Maybe that is something US Shipbuilders should seriously consider. As for the Gowind, Maybe the Gowind Combat Corvette version is what the US Coast Guard should seriously consider as well. The other could be what the Royal Netherlands Navy is getting such as the Holland class offshore patrol vessels.

      http://en.dcnsgroup.com/naval/products/gowind-family/

  6. Tried both. Crane launch over the side, maximum speed 5 knots. Stern launch up to 7 knots is possible so the ship doesnt have to slow down as much.

  7. have not served on an nsc, a good friend commissioned one, as far as mechanical and electrical concerns with the stern launch system, he was much less then impressed. he was mkc.

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